"Senator Obama, this is truly a good day for America," McCain says, looking directly into the camera. "Too often the achievements of our opponents go unnoticed. So I wanted to stop and say, congratulations."

"How perfect that your nomination would come on this historic day," McCain says, referring to the 45th anniversary of Martin Luther King Jr.'s "I Have a Dream" address in Washington. "Tomorrow, we'll be back at it. But tonight senator, job well done."

The 30-second spot aired on national cable TV before, during, and after Obama's acceptance speech Thursday night from Denver is a marked departure from the withering series of ads McCain and Republicans have been running to question Obama's readiness to be president.

McCain also decided to wait till Friday to announcing his pick as a running mate, CNN reported.